Amazon offers over 23,000 Marvel digital comics for Kindle, with prices starting from free. That's tied with our June mention and yields price lows on a wide range of issues. Featured franchises include Avengers, Guardians of the Galaxy, Star Wars, Captain America, X-Men, and Spider-Man.

Amazon again offers its Prime members one early-release Kindle eBook per month for free as part of its Kindle First Program. (It costs $1.99 for non-members who sign up for Kindle First monthly emails.) That's $5 under the list prices of these books, which are otherwise only available as preorders. Deal ends September 30.

Each month, you can choose from one of six new Kindle eBooks that are selected by Amazon's editors in advance of the books' official release dates. This month's titles include Michael Arntfield's "Mad City: The True Story of the Campus Murders That America Forgot", Marius Gabriel's The Designer, and Teresa Driscoll's I Am Watching You.

Amazon offers Prime members a $3 Amazon eBook Credit (good towards select romance novels) for free. (Make sure you are signed into your Prime account when you click the link. The credit will add when you click "redeem credit.") That's the first Amazon eBook credit we've seen that didn't require a purchase. Coupon expire September 30.

LEGO offers its LEGO Club Magazine (6 issues) for free when you create a LEGO ID using your child's date of birth. (An email with further instructions will be sent after you've created the LEGO ID.) You'll receive six issues per year if your child meets the 5-to-10-years-old age requirement.

Mercury Magazines offers a Popular Mechanics 1-Year Subscription (10 issues) for free when you fill out a short form. That's matches our mention from last week for the best price we could find for a 1-year subscription to this magazine by $7.

Amazon offers Robert A. Caro's On Power Audiobook for free when you sign up for a free 30 day trial of Amazon Audible. That's $15 off list and the lowest price we could find. It's narrated by the author.

Note: Be sure to cancel your free trial before 30 days to avoid being charged $14.95 per month.

Amazon continues to discount a selection of Step Into Reading paperback kids' books, with deals starting from $1.90. Plus, Prime members bag free shipping. That puts many items under $3, tying or beating many of their respective Kindle editions' prices. A couple of best bets: